[Bug] Longtblr and preto on multiline cell

[mariuslp]

Tell us about the system on which the bug was produced

• Distribution and year (e.g., TeXLive 2025): TexLive2025
• Engine used (e.g., LuaLaTeX): pdfLatex
• Operating system (e.g., Gentoo Linux): Whatever Overleaf uses

Please outline the bug as you have found it

In a longtblr, the preto command conflicts with width computation when dealing with a multiline. The issue persists with the dev branch.

\documentclass{article}
\usepackage{tabularray}

\begin{document}
\begin{longtblr}[]{
   cell{arrow} = {preto={\hspace{1em}$\hookrightarrow$ }},
   vlines,
}
    a & b & c \\
    \SetChild{class=arrow}{Text on\\ several lines} &1& 2
\end{longtblr}
\end{document}

We see all the white space here that more or less corresponds to the width of the multiline cell, if it were displayed on one line.

Also, is there a way to add a leftsep, or any kind of margin, to a single cell? Ideally in the MWE above I'd like the newline of text to be aligned with the arrow.

Ensure you have filled out all the necessary details

• System information
• Outline of the bug, including MWE for reproduction

[mariuslp]

Also, if we add a \centering before the longtblr environment, the combination centering + longtblr + preto + multiline crashes tabularray: LaTeX Error: Not allowed in LR mode.

The same is true for the tblr environment.

[quark67]

If you add \UseTblrLibrary{varwidth}, you obtain:

\documentclass{article}
\usepackage{tabularray}
\UseTblrLibrary{varwidth}

\begin{document}
\begin{longtblr}[]{
   cell{arrow} = {preto={\hspace{1em}$\hookrightarrow$ }},
   vlines,
}
    a & b & c \\
    \SetChild{class=arrow}{Text on\\ several lines} &1& 2
\end{longtblr}
\end{document}

Also, with \centering, I you also add \UseTblrLibrary{varwidth}, the crash disappear:

\documentclass{article}
\usepackage{tabularray}
\UseTblrLibrary{varwidth}

\begin{document}
\centering\begin{longtblr}[]{
   cell{arrow} = {preto={\hspace{1em}$\hookrightarrow$ }},
   vlines,
}
    a & b & c \\
    \SetChild{class=arrow}{Text on\\ several lines} &1& 2
\end{longtblr}
\end{document}

[mariuslp]

That makes sense, thanks. I am not really sure why varwidth is not included by default, I assume it is for performance reasons? In any case I'll close this ticket.

[quark67]

I don't know if that is a bug and if \UseTblrLibrary{varwidth} is a workaround of that bug, or if \UseTblrLibrary{varwidth} is the good way to deal with your code, but as this is not really documented (I think) in the manual, it's perhaps a bug, so it's perhaps better to keep this issue open so that a official answer from the tabularray team can be obtained.

[mariuslp]

The manual says that varwidth is to be used in case of issues when the "cell contains some vertical material", so I assume that the \\ does qualify for this. For me since the doc already mentions this issue, the underlying question would rather be "should we not incorporate varwidth by default in tabularray", but that is I think a deeper question.

Reopening just so the devs can give their opinion but I'm fine with just closing the issue.